1. Field of the Disclosure
The present disclosure relates to an acoustic navigation method and apparatus using a personal digital assistant having a position detecting function, and a headphone including a geomagnetic sensor and an acceleration sensor.
2. Description of Related Art
Hitherto, with regard to pedestrian course guidance navigation by means of sound, an acoustic navigation apparatus as described in Japanese Unexamined Patent Application Publication No. 2002-5675 has been proposed. This apparatus detects a direction where a user faces (rotational direction of the head) as to a direction of travel, and with a headphone, reproduces the direction and distance perspective of a point serving as a target with sound according to a sound source existing in this point using computation by way of a transfer function.
With this technology, a head rotation angle as to a direction of travel of the user (anteroposterior direction of a user's body) is obtained as follows. Specifically, the apparatus detects the shortest distance from the user's left shoulder to the left side portion of the headphone using a well-recognized laser distance detecting method, and also detects the shortest distance from the user's right shoulder to the right side portion of the headphone. Further, the apparatus detects the rotation direction of the head (clockwise or counterclockwise as viewed from the above) using a sensor worn on around the base of the head. Based on these detected two shortest distances and the rotation direction of the head, the head rotation angle as to the user's direction of travel is obtained. Based on this head rotation angle, the position of the sound source is corrected.
Also, the user's direction of travel is obtained based on position information of two points (latitude and longitude) obtained by a position detecting unit (GPS) detecting positions where the user has moved during a short period of time.